Here is the full list of all 27 How to Take Off Your Mask achievements.
You've unlocked all of the Achievements!
You've cleared the "Secret Discussion"!
You've unlocked all of the Movies.
You've cleared Bonus★Human Side 3!
You've unlocked all of the CGs.
You've got the Luccretia Side Ending!
You've cleared Chapter 6★Luccretia Side!
Listen to what I actually feel...
You've cleared Chapter 5★Luccretia Side!
You've cleared Chapter 4★Luccretia Side!
You've cleared Bonus★Luccretia Side 3!
You've cleared Bonus★Luccretia Side 2!
You've cleared Bonus★Luccretia Side 1!
You've unlocked all of the Music tracks.
You've got the Human Side Ending!
You've cleared Chapter 6★Human Side!
You've cleared Chapter 5★Human Side!
Let me take off this "Big Sister" mask...
You've cleared Chapter 4★Human Side!
You've cleared Chapter 4
You've cleared Chapter 3
You've cleared Bonus★Human Side 2!
You've cleared Chapter 2
You've cleared Bonus★Human Side 1!
You've cleared Chapter 1
You've cleared the Prologue!
Transformed into a luccretia for the first time!